Web sites in a wide area network, such as the Internet, which offer merchandise and/or services are visited by net surfers (herein after visitors) looking for the merchandise or service offered by these sites. The mere fact that a certain visitor has visited a certain web site constitutes information characterizing the visitor with respect to the merchandise or service offered by the visited web site. The visited web site may instruct the visitor's surfing program, such as a WEB browser, to store indication of this information in the visitor's computer or other platform used by the visitor, for example by ‘planting’ a cookie or cookies on storage means of the visitor's computer. This characterizing information is valuable for advertisers, who may target their advertisement better using this user's characterizing information. Thus, this valuable information, or data may be traded between a visited web site, herein after a data provider, and advertiser or advertisers who wish to rely on this data for targeted advertising. Similarly advertising network or networks and advertising agencies may be interested in such data. Advertisers and advertising networks and agencies will be referred to herein after as data buyers.
Several schemes may be used for rewarding a data provider for the data he provides. Such schemes may correlate this reward, or profit, to the number of visitors who access the data provider site, the number of visitors that request advertisement content after visiting the data provider's sites or the actual number of clicks that those visitors clicked on advertisements they were exposed to, etc. The term ‘click’ herein after may refer to any action taken by a user while responding to an optional content within an Internet page (as provided by the data buyer) or to activate an optional action in an Internet page (that was displayed to the visitor as result), or the like. Further, advertising campaigns relying on this data may use one or more of several schemes such as the number of times an advertisement is to be presented in a certain web site during a defined period of time; the blend of a certain advertisement within other advertisements which is presented in a certain web site to a certain user, etc.
Further, a data provider may be interested in ensuring that data provided by him is not used against his business interests, for example by presenting advertisements of business competitors in response to data provided by him. A list of entities that are considered such competitors is usually denoted as a “black-list”.
Considering the above, a data provider may find it rather complicated to verify the fulfillment of the agreement, or contract, he has with the data buyer in two aspects. First, if he is properly rewarded for the data he provided to a data buyer. The difficulties to verify a proper reward to a data provider may be due to the fact that the parameters used for calculating the reward are usually not available to a data provider. Second, in cases where the data provider has asserted ‘negative conditions’ for the use of the data provided by him, for example, preventing the use of such data to invoke advertisements of his or her competitors (defined as part of the ‘black list’ as described above). There is a need for tools that will enable verifying or evaluating the above